of the ancient supercontinent Gondwana 80
million years ago and has been adrift ever
since. During its long solitude it went through
periods of submergence, when all that showed
above the waves was a string of low, swampy
islands, and through episodes of mountain
building. It wandered between the tropics and
the South Pole and endured tens of thousands
of years in the deep freeze of glaciation.
Remarkably, many of the original players
stayed at the table: the iguana-like tuatara,
its slo-mo metabolism ticking away quietly
while the land rose and fell around it; primitive
earless frogs that lack webbing between their
toes and can't croak; and the legendary moa
-11
species ranging from a 40-pound mini
cassowary to the long-necked Dinornisgigan
teus, a quarter of a ton in weight and six feet
high at the top of its back, possibly the tallest
bird ever to walk the Earth.
The only newcomers were those that could
fly or float their way across the oceanic barrier.
Other than bats, no mammals succeeded in
doing that, but dozens of birds did, including
the ancestors of the kiwi and kakapo. Over the
centuries many of these new arrivals, encoun
tering no mammalian predators to harass
them, went to ground. By the time humans
arrived, a third of New Zealand's birds were
either flightless or aerodynamically challenged.
Many species-vertebrate and invertebrate
-became giants of their kind. Large herbi
vores process food more efficiently than small
ones, and in the absence of other factors (such
as the need to nimbly escape fast-moving pred
ators) bigger is better. From weevils to water
fowl, species after species took this route,
appropriating niches occupied elsewhere by
mammals. In place of deer we had the moa; in
place of cows, the takahe, a heavy grass-eating
rail; in place of mice, the weta.
Cosseted by a benign climate and removed
NATIONAL GEOGRAPHIC, OCTOBER 2002